1998 Cobra T56 Viper Transmission Swap

Lift the Viper T56 into place and start the mounting bolts a few turns before tightening. We supported the tail of the transmission with a bottle jack and a block of wood for the time being. We removed the stock shifter for more clearance as well.

With the transmission bolted up and the clutch cable connected, install the transmission crossmember. Tighten the new mount and adapter plate. Jack up the transmission into place and locate the crossmember mounting brackets. In our case, the subframe connectors were in the way just a hair, forcing us to notch the mounting brackets for clearance. Once the mount brackets are measured and set in place, clamp them with locking pliers and MIG-weld them to the framerails.

The T56 takes Dexron III automatic transmission fluid or an equivalent, unlike other Tremec models that require GM Syncromesh fluid. We used Royal Purple Synchromax with Synerlec. It's equivalent to Dexron III yet it reportedly has the additional properties of a full synthetic, with lower gear noise and better shifting. Fill to just below the fill-plug opening. Make sure the factory-installed drain plug is tight and secure as well.

The D&D T56 kits--Viper or otherwise--come with the correct 31-spline output yoke to be mated to the shortened driveshaft. Since we opted for one of D&D's high-quality aluminum shafts ($399)--preshortened and balanced with the proper yoke and flange for our project car--we didn't need to make the trip to a driveshaft shop.

With the driveshaft in place, all that's left is to finish reinstalling the exhaust. As you can see here, the T56 leaves plenty of room for a larger exhaust, converters, or even long-tube headers. With the transmission harness now on the passenger side of the tranny, there's still plenty of length to route the harness back to the rear oxygen sensors by adding a few tie-wraps.

With the kind of power on tap under Editor Turner's right foot (not that he uses it), it's a must to have a quality billet shifter that takes the abuse of banging gears (for when Johnson drives) and that can protect the internal shift forks with built in shifter stops. D&D's T56 shifter ($149) fills the need nicely and makes for one-stop shopping as well. Setting the shifter stops takes just a few seconds with two 1/2-inch wrenches. Now the rest of the shifter trim, handle, weather seal, boot, and knob can go back on.